The present invention relates generally to needleless fluid connection devices, and more specifically to a device for repeatedly establishing a sealed connection to a conduit or a container for medical applications.
One very prevalent form of health care therapy is infusion or intravenous (xe2x80x9cI.V.xe2x80x9d) therapy, whereby fluids possessing desired medication or other characteristics are infused into a patient over varying lengths of time. To practice this infusion therapy, frequently a connection needs to be made for the transfer of fluid between two components, along a fluid passageway and eventually to a patient. As an example, administration sets are widely used to administer liquids parenterally to a patient and other medical devices are connected to the administration set to provide the proper administration.
One widely used connector for making such connections is a luer connection assembly. In the luer connection assembly, a male luer tip component or fitting having a frustoconical shape is inserted into a female luer component or fitting having a frustoconical shaped receiving cavity. Opposing conical surfaces come into contact with each other to form a sealed friction fit.
Until the connection is made, the passageway through each of the luer fittings and into the lumen of a component attached to the luer fitting is open to the environment. This lumen, and the passageway through the luer connectors, form a portion of the fluid passageway and must be sterile prior to use. During use, the lumen and passageway must be sealed against microbial ingress during use. Thus, these connection assemblies and the associated components are packaged in sterile packaging and the connections are typically made just prior to establishing fluid communication with a patient""s venous system.
There are two general types of luer connection assemblies. One type is generally referred to as the luer slip, where the connection is maintained by the friction fit between the male luer tip and female luer component. The other type is generally referred to as a luer lock connection, whereby the male luer tip is encircled by an annular locking flange having a threaded internal surface. The female component includes a corresponding thread formed about the outer surface. Engaging the threaded flange to the threaded outside surface establishes the connection between the male luer tip and female component while preventing accidental disconnects.
To insure a universal luer connection among components provided by various manufacturers, universal standards have been developed, designated by American National Standards Institute, Inc. (ANSI) and International Organization for Standardization (ISO). These standards include prescribed dimensions for male slip and luer lock assemblies. These standards include the thread pitch (threads per inch) of the respective couplings.
Other standards in the ISO regulations include performance requirements for luer connections. One such requirement is that after a luer lock type connection is made, to prevent inadvertent disconnection, the luer connection should resist an axial removal force of 8 pounds and an unscrewing torque of at least 3 in-oz without disconnection. The luer connection should also hold a seal against 45 psi after a connection torque of 16 in-oz has been applied. In luer slip connections, the unscrewing torque is supplied by the friction between the mated, opposing conical surfaces.
Once a component of I.V. therapy is placed in fluid communication with the body, the fluid passageway should be sealed from the environment to prevent contamination, and this passageway should also be sealed so as to not allow any leakage of bodily fluids into the environment. However, most therapies require periodic access to the fluid passageway. Because the portion of the fluid passageway through a female luer connection component is open to the environment, these components will not form a sealed connection to the fluid passageway unless the fluid passageway is placed in fluid communication with the body by means of a male luer connector.
In one prevalent example of intravenous therapy, fluid containing a drug in solution is injected into a primary flow of fluid from an I.V. solution container through an administration set to a catheter extending within a vein. The drug containing fluid may be injected from a syringe, secondary medication set or the like, into the set where it mixes with the flowing fluid. In another example, fluid is injected directly into or withdrawn from a catheter extending within the body. In addition, the catheters are flushed periodically to maintain patency by the injection of small amounts of saline or heparin.
As can be appreciated, it is highly desirable to maintain catheters and administration sets in service as long as possible without compromising the safety of the patient. Replacement of catheters and sets is time consuming and expensive. Therefore, over the period of time of use of a set or catheter there may be many connections and disconnects. For example, there may be over 100 connections and disconnects to a connection site on a catheter or set before the catheter or set is replaced. In addition, a connection may be made and that connection maintained for an extended period of time before disconnection. For example, a connection may be made for up to seven days of xe2x80x9cindwellxe2x80x9d and yet the connection should still be capable of accepting intermediate and subsequent connections and disconnects without allowing leakage to the environment.
To facilitate repeated connections which are sufficiently secure to meet prescribed industry and medical standards, the thread design of the luer fittings must be easy to manipulate by medical personnel, while still providing a strong and sturdy connection.
A known design criteria of luer lock fittings is that it is common for there to be at least as much as a 0.0188 inch difference in thread tolerances between the threads of various manufacturers. Thus, some luer thread engagements will be relatively looser or xe2x80x9csloppierxe2x80x9d than others. Thus, the engagement of the threads may not supply the desired unscrewing torque. On the other hand, if the thread engagement is too tight, excessive stress may be exerted on the locking flange extending about the male luer fitting, and the flange may be cracked or otherwise damaged.
Thus, there is a need for a threaded or luer lock coupling which better accommodates a range of thread dimensions to preserve the sealing characteristics of the connection.
Accordingly, a main object of the present invention is to provide an improved threaded luer lock coupling which is configured to maintain thread interference between adjacent threads of a male and female luer fittings.
Another object of the present invention is to provide an improved threaded luer lock coupling featuring the ability to exert an acceptable axial compressive force on the male luer fitting to enhance thread friction and the resulting sealing relationship.
Yet another object of the present invention is to provide an improved threaded luer lock coupling incorporating a resilient member which accommodates adequate tightening torque by the male luer fitting upon the female fitting.
The above-listed objects are met or exceeded by the present luer activated thread coupler, which is designed to enhance the sealing relationship between a male luer fitting and a peripheral catheter or similar medical conduit. To create a thread interference between the respective threads of the male luer fitting and the female or receiving coupler fitting, the present invention features a resilient washer disposed on an externally threaded attachment end of the coupler. When a male luer fitting is threadably engaged on the attachment end, the luer tip engages a penetrable seal on the receiving coupler, establishing fluid communication between the luer fitting and a conduit or catheter. The resilient washer creates an axially directed compressive force against the male luer threads which forces them against the threads of the attachment end, thus enhancing the sealing relationship between the two components. At the same time, excessive radial forces are not exerted upon the locking collar of the male luer fitting.
More specifically, the present invention provides a coupler for receiving a threaded male luer fitting in sealed relationship, and includes a housing having an attachment end, a conduit end opposite the attachment end and defines a central passageway for providing fluid communication between the luer fitting and a conduit. An arrangement is attached to the housing for establishing a sealed connection between a luer tip and the central passageway. The conduit end has a relatively larger diameter than the attachment end and defines a shoulder at a junction of the attachment end and the conduit end. A resilient member is disposed on the attachment end adjacent the shoulder for exerting an axially directed compressive force upon the male luer fitting as it is threadably engaged upon the attachment end.
In the preferred embodiment, the resilient member is a washer which circumscribes the attachment end, however a leaf spring is also contemplated, and the resealable penetrable member is a slitted septum valve with a xe2x80x9cduck-billxe2x80x9d type seal.